Gushers?

I brewed a centennial blonde about 3 months ago. It was my first all grain batch and I had some mash temp control issues (it ended up being way high, around 160). I bottled after about month or so, and I bottled at about 1.018, though since I mashed high, I didn't think it would go down anymore. I opened and drank a few bottles after 1 week and two weeks, and they were carbed, but nothing out of the ordinary. After that though, every bottle I open begins to gush soon after I open the bottle. When you quickly pour it into a glass, you can see tons of bubbles coming out from the beer, and after it gushes over, a thick head forms that stays indefinitely. At first I thought this was an infection, but I haven't changed any of my sanitation procedures, and I haven't encountered this before. To sanitize my bottles, I soak them in oxyclean for a few hours, rinse a few times and then use starsan. I then put them on a sanitized bottle tree. To sanitize my equipment, I use starsan, and I run it through the spigot, tubing and bottling wand.

I primed with 5 ounces of sugar, but I definitely had less that 5 gallons, so it is possible that over carbed, and it also was quite cold (in the low 50s) in the part of the house that the primary was kept in and now it has warmed up considerably.

I know you can't diagnose the problem, but I was wondering if there was anything I could do to minimize my chances of encountering this again.

That FG1.018 was likely a little high & not done yet. That's a common cause of gushers. Also,try leaving them in the fridge for a week. Get more co2 into solution & that sometimes helps. But it's likely over-primed with the high FG combined with priming solution.

That is what I was thinking. I think due to the cold temps, the yeast never really finished up, and then as it warmed up, I think the yeast became more active...oh well

Use your hydrometer and check the final gravity on your carbed beer.You definatly overcarbed in the first place.Your beer should have been done with a month primary,unless it got too cold within the first week or two. Or you have an infection.If you used table(sucrose) sugar then yes you way overcarbed. Clean all tubing/bottleing stuff with pbw or bleach or something or replace plastic tubing/scratched-old buckets.

So, I checked the gravity of the bottled beer, and to my surprise, it was below 1.005. I have never had a beer ferment that low before, but I guess it wasnt done fermenting...

It sounds to me like it got too cold during ferment. I always like to get it up higher temps towards the end of the first week or so of ferment to assure its completly finished. That is where a hydrometer would fail is if you did the 3 day readings but the yeast was still dormant and may have woke up in higher temps-like you said after you bottled. Although the majority of fermention is probably done within a few+ days assuming the appropriate yeast environment.

Be carefull.Get those to the fridge and drink fast if they even pour ok,or pitch them out. Ive had over carbs and infections but luckily no blow outs and actually Ive never had gushers or gysers ( only just slow foamers) and have always got the whole batch right to the fridge. I think another key to infections or overcarbed bottles is to handle them very carefully when moving them or storing them without disturbing the yeast. Ive done this successfully only because I kept an eye on any suspicious overcarbing in the beginning or the first few months of bottleing.Anything that is carefully poured and pours a half glass of foam may be a suspicous batch and should go straight to the fridge. And if you dont like ageing you beers then its just not a bad idea to get them to the fridge after the first month or with adequate carbonation assuming they taste great also.

1.05 makes me think infection. I've had beers overcarb for no apparent reason and they always had low FG after a few months in the bottle. Low FG is what you'd expect if something got in there and fermented what the yeast couldn't.